Radiation curable polyurethanes with capped amino groups

ABSTRACT

Polyurethanes containing at least one free radically or cationically polymerizable unsaturated group and at least one capped amino group.

The invention relates to radiation curable compounds containing cappedamino groups and if desired capped or uncapped isocyanate groups and totheir use in dual cure and multicure systems.

Examples of suitable capping agents for NCO groups include oximes,phenols, imidazoles, pyrazoles, pyrazolinones, diketopiperazines,caprolactam, malonic esters, and compounds as stated in the publicationsby Z. W. Wicks in Prog. Org. Coat. 3 (1975) 73-99 and Prog. Org. Coat 9(1981), 3-28 and also in Houben-Weyl, Methoden der Organischen Chemie,Vol. XIV/2, p. 61 ff., Georg Thieme Verlag, Stuttgart 1963.

Dual cure systems feature curability by two independent curingmechanisms, e.g., by radiation, moisture, oxidative or thermal curing. Aparticular desire is for systems which following application of thecoating material can be precured by very brief irradiation to give afilm which is flexible and dust dry. This film should then either beamenable to a thermal aftercure or should continue to full cure by meansof simple storage for a few days in air until a hard film has developedwhich has the desired ultimate service properties. This type of twostage curing is of particular importance on account of the fact that itoffers coating systems processors the opportunity to coat an articlewith a film in a first workstep and to subject this film to furtherprocessing in a further workstep, in particular by imparting a certainprofile to the coated article following irradiation, using pressure. Itis therefore necessary for the films to be in a precured state when theyare deformed in the second workstep, so that they do not stick to thetools during their deformation, but they must not be so hard that theycrack when stretched and deformed.

The terms “dual cure” and “multicure” refer in accordance with theinvention to a curing operation which is accomplished by way of two ormore than two mechanisms, respectively, with curing taking place bymeans of radiation, moisture, chemicals, oxidation or heat.

WO 00/39183 describes free radically polymerizable compounds containingurethane and allophanate groups and activated C═C double bonds.

Such compounds possess only one curing mechanism, viz. radiation.

DE-A1 196 09 617 and WO 97/23536 describe compounds containingisocyanate groups and capped, isocyanate reactive groups, such asoxazolidines, for one and two component polyurethane coatingcompositions.

Such compounds are only moisture curable, necessitating long cure timesand leading to soft films.

WO 01/83579 describes multicomponent coating systems comprising anadduct of a diisocyanate containing oxazolidine, for example, and a(meth)acrylate copolymer containing hydroxy groups.

In the absence of double bonds, however, the adducts described cannot beradiation cured in the fully polymerized (meth)acrylate copolymer and soneccesitate cure times of generally at least 30 minutes. A radiationcure is only possible when radiation curable components are admixedindependently of the adduct.

DE-A1 100 47 989 describes dual cure multicomponent coating materialswhich comprise an adduct of a urethane formed from hexamethylenediisocyanate, containing isocyanate groups for example, and anoxazolidine and also a hydroxyl-containing and radiation curable(meth)acrylate copolymer. The copolymer used advantageously hasmolecular weights M_(n) of from 1 000 to 20 000 and M_(w) of from 2 000to 100 000 daltons.

A disadvantage of these systems is that owing to the high molecularweights of the copolymer used the resultant adducts also have highmolecular weights and, accordingly, high viscosities.

It is an object of the present invention to provide radiation curabledual cure or multicure systems which have a low viscosity and exhibitgood surface properties.

We have found that this object is achieved by polyurethanes (A)comprising as synthesis components

-   -   a) at least one organic diisocyanate or polyisocyanate,    -   b) at least one compound containing at least one        isocyanate-reactive group and at least one free radically        polymerizable unsaturated group and/or cationically        polymerizable group,    -   c) at least one compound containing at least one        isocyanate-reactive group and at least one capped amino group        and having a molecular weight below 1000 g/mol,    -   d) if desired, at least one compound containing at least one        isocyanate-reactive group and at least one actively dispersing        group,    -   e) if desired, at least one compound containing at least two        isocyanate-reactive groups, and    -   f) if desired, compounds other than a) to d) containing at least        one isocyanate-reactive group.

The number average molecular weight M_(n) of these compounds (A),determined by gel permeation chromatography using tetrahydrofuran eluentand polystyrene standards, can be for example between 200 and 50 000,preferably between 250 and 30 000, more preferably between 350 and 10000, and in particular between 350 and 5 000.

The amount of unsaturated free radically or cationically polymerizablegroups can be for example at least 0.01 mol/100 g compound, preferablyat least 0.05, more preferably at least 0.1, and in particular at least0.2 mol/100 g.

The amount of capped amino groups can be for example at least 0.01mol/100 g compound, preferably at least 0.05, more preferably at least0.1, and in particular at least 0.2 mol/100 g.

The polyurethanes (A) of the invention comprise as synthesis componentsessentially the above-recited components a), b), and c), and also, ifdesired, components d), e), and/or f).

We have found that the aforementioned object is likewise achieved bypolyurethane dispersions which can be processed as aqueous systems andessentially comprise

-   -   (A) a polyurethane which includes component d),    -   (C) if desired, one or more photochemically and/or thermally        activable initiators, and    -   (D) if desired, further typical coatings additives.

The compounds (C) and (D) can also be added to the polyurethanes if itis desired to provide coating formulations for preparing dual curecoating materials.

Suitable components a) include for example aliphatic, aromatic, andcycloaliphatic diisocyanates and polyisocyanates having an NCOfunctionality of at least 1.8, preferably from 1.8 to 5, and morepreferably from 2 to 4, and also their isocyanurates, biurets,urethanes, allophanates, and uretdiones.

The diisocyanates are preferably isocyanates having 4 to 20 carbonatoms. Examples of common diisocyanates are aliphatic diisocyanates suchas tetramethylene diisocyanate, hexamethylene diisocyanate(1,6-diisocyanatohexane), octamethylene diisocyanate, decamethylenediisocyanate, dodecamethylene diisocyanate, tetradecamethylenediisocyanate, derivatives of lysine diisocyanate, trimethylhexanediisocyanate or tetramethylhexane diisocyanate, cycloaliphaticdiisocyanates such as 1,4-, 1,3- or 1,2-diisocyanatocyclohexane, 4,4′-or 2,4′-di(isocyanatocyclohexyl)methane,1-isocyanato-3,3,5-trimethyl-5-(isocyanatomethyl)cyclohexane (isophoronediisocyanate), 1,3- or 1,4-bis(isocyanatomethyl)cyclohexane or 2,4-, or2,6-diisocyanato-1-methylcyclohexane and also aromatic diisocyanatessuch as 2,4- or 2,6-tolylene diisocyanate and the isomer mixturesthereof, m- or p-xylylene diisocyanate, 2,4′- or4,4′-diisocyanatodiphenylmethane and the isomer mixtures thereof, 1,3-or 1,4-phenylene diisocyanate, 1-chloro-2,4-phenylene diisocyanate,1,5-naphthylene diisocyanate, diphenylene 4,4′-diisocyanate,4,4′-diisocyanato-3,3′-dimethylbiphenyl, 3-methyldiphenylmethane4,4′-diisocyanate, tetramethylxylylene diisocyanate,1,4-diisocyanatobenzene or diphenyl ether 4,4′-diisocyanate.

Mixtures of said diisocyanates may also be present.

Examples of suitable common isocyanates containing on average at least 2isocyanate groups include triisocyanates such as2,4,6-triisocyanatotoluene, triphenylmethane triisocyanate or2,4,4′-triisocyanatodiphenyl ether or the mixtures of di-, tri-, andhigher polyisocyanates which are obtained by phosgenating correspondinganiline/formaldehyde condensates and constitute polyphenylpolyisocyanates with methylene bridges.

Suitable polyisocyanates include polyisocyanates containing isocyanurategroups, uretdione diisocyanates, polyisocyanates containing biuretgroups, polyisocyanates containing urethane or allophanate groups,polyisocyanates containing oxadiazinetrione or iminooxadiazinedionegroups, uretonimine-modified polyisocyanates of straight-chain orbranched C₄-C₂₀ alkylene diisocyanates, cycloaliphatic diisocyanateshaving 6 to 20 carbon atoms in all or aromatic diisocyanates having 8 to20 carbon atoms in all, or mixtures thereof.

The diisocyanates and polyisocyanates which can be used preferably havean isocyanate group content (calculated as NCO, molecular weight=42) offrom 10 to 60% by weight, based on the diisocyanate and polyisocyanate(mixture), more preferably from to 60% by weight, and very preferablyfrom 20 to 55% by weight.

Preference is given to aliphatic and/or cycloaliphatic diisocyanates andpolyisocyanates, examples being the aliphatic and cycloaliphaticdiisocyanates, respectively, that have been mentioned above, or tomixtures thereof.

Hexamethylene diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane,isophorone diisocyanate, and di(isocyanatocyclohexyl)methane, areparticularly preferred, isophorone diisocyanate and hexamethylenediisocyanate are very particularly preferred, and hexamethylenediisocyanate is especially preferred.

Preference is extended to

-   1) polyisocyanates containing isocyanurate groups and derived from    aromatic, aliphatic and/or cycloaliphatic diisocyanates.

Particularly preferred here are the corresponding aliphatic and/orcycloaliphatic isocyanato isocyanurates and in particular those based onhexamethylene diisocyanate and isophorone diisocyanate. Theisocyanurates present are, in particular, trisisocyanatoalkyl ortrisisocyanatocycloalkyl isocyanurates, which constitute cyclic trimersof the diisocyanates, or mixtures with their higher homologs containingmore than one isocyanurate ring. The isocyanato isocyanurates generallyhave an NCO content of from 10 to 30% by weight, in particular from 15to 25% by weight, and an average NCO functionality of from 2.6 to 4.5.

-   2) Uretdione diisocyanates having aromatically, aliphatically and/or    cycloaliphatically attached isocyanate groups, preferably    aliphatically and/or cycloaliphatically attached groups, and in    particular those derived from hexamethylene diisocyanate or    isophorone diisocyanate. Uretdione diisocyanates are cyclic    dimerization products of diisocyanates. In the formulations of the    invention the uretdione diisocyanates can be used as a component    alone or in a mixture with other polyisocyanates, particularly those    specified under 1).

3) Polyisocyanates containing biuret groups and having aromatically,cycloaliphatically or aliphatically, preferably cycloaliphatically oraliphatically, attached isocyanate groups, especiallytris(6-isocyanatohexyl)biuret or its mixtures with its higher homologs.These polyisocyanates containing biuret groups generally have an NCOcontent of from 18 to 22% by weight and an average NCO functionality offrom 2.8 to 4.5.

4) Polyisocyanates containing urethane and/or allophanate groups andaromatically, aliphatically or cycloaliphatically, preferablyaliphatically or cycloaliphatically, attached isocyanate groups, as areobtainable for example by reacting excess amounts of hexamethylenediisocyanate or of isophorone diisocyanate with monohydric or polyhydricalcohols such as methanol, ethanol, iso-propanol, n-propanol, n-butanol,iso-butanol, sec-butanol, tert-butanol, n-hexanol, n-heptanol,n-octanol, n-decanol, n-dodecanol (lauryl alcohol), 2-ethylhexanol,n-pentanol, stearyl alcohol, cetyl alcohol, lauryl alcohol, ethyleneglycol monomethyl ether, ethylene glycol monoethyl ether,1,3-propanediol monomethyl ether, cyclopentanol, cyclohexanol,cyclooctanol, cyclododecanol, trimethylolpropane, neopentylglycol,pentaerythritol, 1,4-butanediol, 1,6-hexanediol, 1,3-propanediol,2-ethyl-1,3-propanediol, 2-methyl-1,3-propanediol, ethylene glycol,diethylene glycol, triethylene glycol, tetraethylene glycol,pentaethylene glycol, glycerol, 1,2-dihydroxypropane,2,2-dimethyl-1,2-ethanediol, 1,2-butanediol, 1,4-butanediol,3-methylpentane-1,5-diol, 2-ethylhexane-1,3-diol,2,4-diethyloctane-1,3-diol, neopentylglycol hydroxypivalate,ditrimethylolpropane, dipentaerythritol,2,2-bis(4-hydroxycyclohexyl)propane, 1,1-, 1,2-, 1,3- and1,4-cyclohexanedimethanol, 1,2-, 1,3- or 1,4-cyclohexanediol or mixturesthereof. These polyisocyanates containing urethane and/or allophanategroups generally have an NCO content of from 12 to 20% by weight and anaverage NCO functionality of from 2.5 to 4.5.

-   5) Polyisocyanates containing oxadiazinetrione groups, preferably    derived from hexamethylene diisocyanate or isophorone diisocyanate.    Polyisocyanates of this kind containing oxadiazinetrione groups can    be prepared from diisocyanate and carbon dioxide.-   6) Polyisocyanates containing iminooxadiazinedione groups,    preferably derived from hexamethylene diisocyanate or isophorone    diisocyanate. Polyisocyanates of this kind containing    iminooxadiazinedione groups can be prepared from diisocyanates by    means of specific catalysts.-   7) Uretonimine-modified polyisocyanates.

Polyisocyanates 1) to 7) can be used in a mixture, including whereappropriate a mixture with diisocyanates.

Suitable components b) are compounds which carry at least oneisocyanate-reactive group and at least one free radically orcationically polymerizable group.

Examples of possible isocyanate-reactive groups include —OH, —SH, —NH₂and —NHR⁴, with R⁴ being hydrogen or C₁-C₄ alkyl.

C₁-C₄ Alkyl for the purposes of this specification means methyl, ethyl,iso-propyl, n-propyl, n-butyl, iso-butyl, sec-butyl or tert-butyl.

Polymerizable groups can be those which have unsaturated bonds,preferably carbon-carbon double bonds.

Free radically polymerizable groups are for example isolatedethylenically unsaturated groups, conjugated unsaturated groups,vinylaromatic groups, groups of vinyl chloride and vinylidene chloridetype, N-vinyl amides, vinylpyrrolidones, vinyllactams, vinyl esters,(meth)acrylic esters or acrylonitriles.

Examples of cationically polymerizable groups include isobutylene unitsand vinyl ethers.

Examples of components b) are monoesters of α,β-unsaturated carboxylicacids, such as acrylic acid, methacrylic acid (referred to together inthis specification as “(meth)acrylic acid” for short), crotonic acid,itaconic acid, fumaric acid, maleic acid, acrylamidoglycolic acid,methacrylamidoglycolic acid or vinyl ethers with diols or polyols havingpreferably 2 to 20 carbon atoms and at least two hydroxyl groups, suchas ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propyleneglycol, 1,3-propylene glycol, 1,1-dimethyl-1,2-ethanediol, dipropyleneglycol, triethylene glycol, tetraethylene glycol, pentaethylene glycol,tripropylene glycol, 1,4-butanediol, 1,5-pentanediol, neopentylglycol,neopentylglycol hydroxypivalate, 2-ethyl-1,3-propanediol,2-methyl-1,3-propanediol, 1,6-hexanediol, 2-methyl-1,5-pentanediol,2-ethyl-1,4-butanediol, 2-ethyl-1,3-hexanediol,2,4-diethyloctane-1,3-diol, 2,2-bis(4-hydroxycyclohexyl)propane, 1,1-,1,2-, 1,3- and 1,4-bis(hydroxymethyl)cyclohexane, 1,2-, 1,3- or1,4-cyclohexanediol, glycerol, trimethylolethane, trimethylolpropane,trimethylolbutane, pentaerythritol, ditrimethylolpropane,dipentaerythritol, sorbitol, mannitol, diglycerol, threitol, erythritol,adonitol (ribitol), arabitol (lyxitol), xylitol, dulcitol (galactitol),maltitol, Isomalt, polyTHF having a molar weight of between 162 and 378,poly-1,3-propanediol or polypropylene glycol with a molar weight between134 and 400 or polyethylene glycol with a molar weight between 238 and458. It is also possible to use esters or amides of (meth)acrylic acidwith amino alcohols, e.g., 2-aminoethanol, 2-(methylamino)ethanol,3-amino-1-propanol, 1-amino-2-propanol or 2-(2-aminoethoxy)ethanol,2-mercaptoethanol or polyaminoalkanes, such as ethylenediamine ordiethylenetriamine, or vinylacetic acid as well.

Also suitable in addition are unsaturated polyetherols or polyesterolsor polyacrylate polyols having an average OH functionality of from 2 to10.

Examples of amides of ethylenically unsaturated carboxylic acids withamino alcohols are hydroxyalkyl(meth)acrylamides such asN-hydroxymethylacrylamide, N-hydroxymethylmethacrylamide,N-hydroxyethylacrylamide, N-hydroyxethylmethacrylamide,5-hydroxy-3-oxapentyl(meth)acrylamide, N-hydroxyalkylcrotonamides suchas N-hydroxymethylcrotonamide or N-hydroxyalkylmaleimides such asN-hydroxyethylmaleimide.

Preference is given to using 2-hydroxyethyl (meth)acrylate, 2- or3-hydroxypropyl (meth)acrylate, 1,4-butanediol mono(meth)acrylate,neopentylglycol mono(meth)acrylate, glyceryl mono- and di(meth)acrylate,trimethylolpropane mono- and di(meth)acrylate, pentaerythrityl mono-,di- and tri(meth)acrylate, and also 4-hydroxybutyl vinyl ether,2-aminoethyl (meth)acrylate, 2-aminopropyl (meth)acrylate, 3-aminopropyl(meth)acrylate, 4-aminobutyl (meth)acrylate, 6-aminohexyl(meth)acrylate, 2-thioethyl (meth)acrylate, 2-aminoethyl (meth)acrylamide, 2-aminopropyl (meth)acrylamide, 3-aminopropyl(meth)acrylamide, 2-hydroxyethyl (meth)acrylamide, 2-hydroxypropyl(meth)acrylamide or 3-hydroxypropyl (meth)acrylamide. Particularpreference is given to 2-hydroxyethyl acrylate, 2-hydroxyethylmethacrylate, 2- or 3-hydroxypropyl acrylate, 1,4-butanediolmonoacrylate and 3-(acryloyloxy)-2-hydroxypropyl methacrylate.

Compounds suitable as component c) are those containing at least oneisocyanate-reactive group and at least one capped amino group, with amolecular weight below 1000 g/mol, preferably below 750 g/mol, morepreferably below 500 g/mol, and in particular below 250 g/mol.

Capped amino groups are those from which unsubstituted ormonosubstituted amino groups can be liberated, and include, for example,open-chain or cyclic aminals, N,O-acetals, N,O-ketals, ketimines,aldimines, carboxamides, sulfonamides or amidines, preferably ketimines,aldimines, aminals, N,O-acetals, N,O-ketals or amidines, with particularpreference aminals, ketimines, aldimines, N,O-acetals or N,O-ketals, andespecially N,O-acetals.

Within this specification the term “capped” means that the structure inquestion, an amino group for example, is essentially stable under thereaction conditions of the preparation of the polyurethanes of theinvention and of the radiation curable compositions and that it is onlyunder the conditions of curing that the group is decomposed to effectsignificant liberation of the structure in question. “Essentiallystable” here means that under the reaction conditions less than 10 mol %per hour, preferably less than 5 mol %/h, more preferably less than 2mol %/h, and very preferably less than 1 mol %/h is decomposed.

Preferred compounds containing capped amino groups are oxazolidines,aldimines, and ketimines, as known for example from EP-A1 659 791, p. 6,line 26 to p. 7, line 13 and the examples, and from U.S. Pat. No.5,922,804, col. 1, line 42 to col. 3, line 45, oxazolidines beingparticularly preferred.

The compounds c) may contain one or more capped amino groups, forexample from 1 to 3, preferably from 1 to 2, and more preferably 1.

The compounds c) can contain one or more isocyanate-reactive groups, forexample, from 1 to 3, preferably 1 or 2, and more preferably 1.

Compounds c) can for example be compounds containing at least one ringnitrogen atom that are of the type set out in DE-A1 196 09 617 on p. 2,line 31-59 and especially on p. 3 lines 33-55, or oxazolidines asdescribed in DE-A 22 45 636 on p. 2 line 5 to p. 3 para. 3 and inExamples 1, 2, 5, 6 and 9.

Both documents are hereby expressly included in the present disclosurecontent by reference.

The preparation of β-hydroxyalkyloxazolidines is described in DE-A 22 45636 on p. 3, para. 3 to p. 4 para. 1.

Preferred components c) are compounds of the formula (I),

where

-   R and R² independently are each a divalent organic aliphatic,    cycloaliphatic or aromatic radical containing 2 to 20 carbon atoms    which is unsubstituted or substituted by functional groups, aryl,    alkyl, aryloxy, alkyloxy, halogen, heteroatoms and/or heterocycles,-   R¹ and R¹′ independently are each hydrogen, C₁-C₁₈ alkyl, C₂-C₁₈    alkyl which is uninterrupted or interrupted by one or more oxygen    and/or sulfur atoms and/or by one or more substituted or    unsubstituted imino groups, or is C₆-C₁₂ aryl, C₅-C₁₂ cycloalkyl or    a five- or six-membered heterocycle containing oxygen, nitrogen    and/or sulfur atoms, it being possible for each of said radicals to    be substituted by functional groups, aryl, alkyl, aryloxy, alkyloxy,    halogen, heteroatoms and/or heterocycles,-   X is oxygen (—O—), unsubstituted or monosubstituted nitrogen (>NR⁴)    or >N—NR⁴R⁵,-   Y is oxygen (—O—), unsubstituted nitrogen (>NH) or sulfur (—S—), and-   R⁴ and R⁵ independently are each hydrogen or C₁-C₄ alkyl.

Examples of R and R² are 1,2-ethylene, 1,2-propylene,2-methyl-1,2-propylene, 1-phenyl-1,2-ethylene,2′-aminoethyl-1,2-ethylene, 1-iso-propyl-1,2-ethylene,1-tert-butyl-1,2-ethylene, 1-benzyl-1,2-ethylene,1-phenyl-2-methyl-1,2-ethylene, 1-phenyl-2-methoxymethyl-1,2-ethylene,but-1-en-3,4-ylene, 1,3-propylene, 2-methyl-1,3-propylene,2-ethyl-1,3-propylene, 1,4-butylene, 1,6-hexylene,2,2-dimethyl-1,3-propylene, 2,2-dimethyl-1,4-butylene, 1,1-, 1,2-, 1,3-or 1,4-cyclohexylene, 1,2- or 1,3-cyclopentylene, 1,2-, 1,3- or1,4-phenylene, 4,4′-biphenylene or 3-oxa-1,5-pentylene.

Preferably R and R² are each independently 1,2-ethylene, 1,2-propylene,2-methyl-1,2-propylene or 1,3-propylene, more preferably 1,2-ethylene or1,2-propylene, and very preferably 1,2-ethylene.

R¹ and R¹′ may independently each for example be hydrogen, methyl,ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, pentyl, hexyl,heptyl, octyl, 2-ethylhexyl, 2,4,4-trimethylpentyl, 2-methoxyethyl,2-ethoxyethyl, 2-butoxyethyl, chloromethyl, 2-chloroethyl,trichloromethyl, trifluoromethyl, vinyl, 1-propenyl, benzyl, phenyl,tolyl, chlorophenyl, dichlorophenyl, 2,6-dimethylphenyl,2,4,6-trimethylphenyl, 2,6-dimethoxyphenyl, 2,6-dichlorophenyl,cyclopentyl, cyclohexyl or furyl.

Preferably R¹ and R¹′ each independently are hydrogen, methyl, ethyl,propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, phenyl, cyclopentyl,cyclohexyl or furyl, more preferably R¹ is hydrogen, methyl, ethyl,propyl or isopropyl and R¹′ is hydrogen, methyl or ethyl, verypreferably R¹ is hydrogen, methyl or iso-propyl, and especiallyiso-propyl, and R¹′ is hydrogen, or R¹ and R¹′ are both methyl.

X is preferably oxygen (—O—) or unsubstituted or monosubstitutednitrogen (>NR⁴) and with particular preference oxygen.

Y is preferably oxygen (—O—) or unsubstituted nitrogen (>NH) and withparticular preference oxygen.

Particularly preferred components c) are

-   N-(2′-hydroxyethyl)-oxazolidine,-   N-(2′-hydroxyethyl)-2-methyloxazolidine,-   N-(2′-hydroxyethyl)-2-ethyloxazolidine,-   N-(2′-hydroxyethyl)-2-iso-propyloxazolidine,-   N-(2′-hydroxyethyl)-2-propyloxazolidine,-   N-(2′-hydroxyethyl)-2-phenyloxazolidine,-   N-(2′-hydroxyethyl)-2,2-dimethyloxazolidine,-   N-(2′-hydroxyethyl)-2,2-diethyloxazolidine,-   N-(2′-hydroxyethyl)-4-methyloxazolidine,-   N-(2′-hydroxyethyl)-2,4-dimethyloxazolidine,-   N-(2′-hydroxyethyl)-2-ethyl-4-methyloxazolidine,-   N-(2′-hydroxyethyl)-2-iso-propyl-4-methyloxazolidine,-   N-(2′-hydroxyethyl)-2-propyl-4-methyloxazolidine,-   N-(2′-hydroxyethyl)-2-phenyl-4-methyloxazolidine,-   N-(2′-hydroxyethyl)-2,2,4-trimethyloxazolidine,-   N-(2′-hydroxyethyl)-5-methyloxazolidine,-   N-(2′-hydroxyethyl)-2,5-dimethyloxazolidine,-   N-(2′-hydroxyethyl)-2-ethyl-5-methyloxazolidine,-   N-(2′-hydroxyethyl)-2-isopropyl-5-methyloxazolidine,-   N-(2′-hydroxyethyl)-2-propyl-5-methyloxazolidine,-   N-(2′-hydroxyethyl)-2-phenyl-5-methyloxazolidine,-   N-(2′-hydroxyethyl)-2,2,5-trimethyloxazolidine,-   N-(2′-hydroxyethyl)-4,4-methyloxazolidine,-   N-(2′-hydroxyethyl)-2,4,4-trimethyloxazolidine,-   N-(2′-hydroxyethyl)-2-ethyl-4,4-dimethyloxazolidine,-   N-(2′-hydroxyethyl)-2-isopropyl-4,4-dimethyloxazolidine,-   N-(2′-hydroxyethyl)-2-propyl-4,4-dimethyloxazolidine,-   N-(2′-hydroxyethyl)-2-phenyl-4,4-dimethyloxazolidine,-   N-(2′-hydroxyethyl)-2,2,4,4-tetramethyloxazolidine,-   N-(2′-hydroxypropyl)oxazolidine,-   N-(2′-hydroxypropyl)-2-methyloxazolidine,-   N-(2′-hydroxypropyl)-2-ethyloxazolidine,-   N-(2′-hydroxypropyl)-2-isopropyloxazolidine,-   N-(2′-hydroxypropyl)-2-propyloxazolidine,-   N-(2′-hydroxypropyl)-2-phenyloxazolidine,-   N-(2′-hydroxypropyl)-2,2-dimethyloxazolidine,-   N-(2′-hydroxypropyl)-4-methyloxazolidine,-   N-(2′-hydroxypropyl)-2,4-dimethyloxazolidine,-   N-(2′-hydroxypropyl)-2-ethyl-4-methyloxazolidine,-   N-(2′-hydroxypropyl)-2-isopropyl-4-methyloxazolidine,-   N-(2′-hydroxypropyl)-2-propyl-4-methyloxazolidine,-   N-(2′-hydroxypropyl)-2-phenyl-4-methyloxazolidine,-   N-(2′-hydroxypropyl)-2,2,4-trimethyloxazolidine,-   N-(2′-hydroxypropyl)-5-methyloxazolidine,-   N-(2′-hydroxypropyl)-2,5-dimethyloxazolidine,-   N-(2′-hydroxypropyl)-2-ethyl-5-methyloxazolidine,-   N-(2′-hydroxypropyl)-2-isopropyl-5-methyloxazolidine,-   N-(2′-hydroxypropyl)-2-propyl-5-methyloxazolidine,-   N-(2′-hydroxypropyl)-2-phenyl-5-methyloxazolidine,-   N-(2′-hydroxypropyl)-2,2,5-trimethyloxazolidine,-   N-(2′-hydroxypropyl)-4,4-methyloxazolidine,-   N-(2′-hydroxypropyl)-2,4,4-trimethyloxazolidine,-   N-(2′-hydroxypropyl)-2-ethyl-4,4-dimethyloxazolidine,-   N-(2′-hydroxypropyl)-2-isopropyl-4,4-dimethyloxazolidine,-   N-(2′-hydroxypropyl)-2-propyl-4,4-dimethyloxazolidine,-   N-(2′-hydroxypropyl)-2-phenyl-4,4-dimethyloxazolidine,-   N-(2′-hydroxypropyl)-2,2,4,4-tetramethyloxazolidine,-   N-(3′-hydroxypropyl)oxazolidine,-   N-(3′-hydroxypropyl)-2-methyloxazolidine,-   N-(3′-hydroxypropyl)-2-ethyloxazolidine,-   N-(3′-hydroxypropyl)-2-isopropyloxazolidine,-   N-(3′-hydroxypropyl)-2-propyloxazolidine,-   N-(3′-hydroxypropyl)-2-phenyloxazolidine,-   5N-(3′-hydroxypropyl)-2,2-dimethyloxazolidine,-   N-(3′-hydroxypropyl)-4-methyloxazolidine,-   N-(3′-hydroxypropyl)-2,4-dimethyloxazolidine,-   N-(3′-hydroxypropyl)-2-ethyl-4-methyloxazolidine,-   N-(3′-hydroxypropyl)-2-isopropyl-4-methyloxazolidine,-   N-(3′-hydroxypropyl)-2-propyl-4-methyloxazolidine,-   N-(3′-hydroxypropyl)-2-phenyl-4-methyloxazolidine,-   N-(3′-hydroxypropyl)-2,2,4-trimethyloxazolidine,-   N-(3′-hydroxypropyl)-5-methyloxazolidine,-   N-(3′-hydroxypropyl)-2,5-dimethyloxazolidine,-   N-(3′-hydroxypropyl)-2-ethyl-5-methyloxazolidine,-   N-(3′-hydroxypropyl)-2-isopropyl-5-methyloxazolidine,-   N-(3′-hydroxypropyl)-2-propyl-5-methyloxazolidine,-   N-(3′-hydroxypropyl)-2-phenyl-5-methyloxazolidine,-   N-(3′-hydroxypropyl)-2,2,5-trimethyloxazolidine,-   N-(3′-hydroxypropyl)-4,4-methyloxazolidine,-   N-(3′-hydroxypropyl)-2,4,4,4-trimethyloxazolidinde,-   N-(3′-hydroxypropyl)-2-ethyl-4,4-dimethyloxazolidine,-   N-(3′-hydroxypropyl)-2-isopropyl-4,4-dimethyloxazolidine,-   N-(3′-hydroxypropyl)-2-propyl-4,4-dimethyloxazolidine,-   N-(3′-hydroxypropyl)-2-phenyl-4,4-dimethyloxazolidine or-   N-(3′-hydroxypropyl)-2,2,4,4-tetramethyloxazolidine.

Those especially preferred are N-(2′-hydroxyethyl)oxazolidine,

-   N-(2′-hydroxyethyl)-2-methyloxazolidine,-   N-(2′-hydroxyethyl)-2-ethyloxazolidine,-   N-(2′-hydroxyethyl)-2-isopropyloxazolidine,-   N-(2′-hydroxyethyl)-2,2-dimethyloxazolidine,-   N-(2′-hydroxypropyl)oxazolidine,-   N-(2′-hydroxypropyl)-2-methyloxazolidine,-   N-(2′-hydroxypropyl)-2-ethyloxazolidine,-   N-(2′-hydroxypropyl)-2-isopropyloxazolidine,-   N-(2′-hydroxypropyl)-2,2-dimethyloxazolidine, with particular    preference being given to N-(2′-hydroxyethyl)oxazolidine,-   N-(2′-hydroxyethyl)-2-isopropyloxazolidine, and-   N-(2′-hydroxyethyl)-2,2-dimethyloxazolidine.

Compounds suitable as component d) are those having at least oneisocyanate-reactive group and at least one actively dispersing group.

Such compounds are represented for example by the general formulaRG-R³-DGwhere

-   RG is at least one isocyanate-reactive group,-   DG is at least one actively dispersing group, and-   R³ is an aliphatic, cycloaliphatic or aromatic radical containing 1    to 20 carbon atoms.

Examples of isocyanate-reactive groups RG are —OH, —SH, —NH₂ and —NHR⁴,in which R⁴ is as defined earlier but may be different from the radicalused earlier on.

Examples of DG are —COOH, —SO₃H and —PO₃H and their anionic forms, withwhich any desired counterion may be associated, e.g., Li⁺, Na⁺, K⁺, Cs⁺,Mg²⁺, Ca²⁺, Ba²⁺, ammonium, methylammonium, dimethylammonium,trimethylammonium, ethylammonium, diethylammonium, triethylammonium,tributylammonium, di-iso-propylethylammonium, benzyldimethylammonium,monoethanolammonium, diethanolammonium, triethanolammonium,hydroxyethyldimethylammonium, hydroxyethyldiethylammonium,monopropanolammonium, dipropanolammonium, tripropanolammonium,piperidinium, piperazinium, N,N′-dimethylpiperazinium, morpholinium orpyridinium.

R³ can for example be methylene, 1,2-ethylene, 1,2-propylene,1,3-propylene, 1,2-butylene, 1,4-butylene, 1,3-butylene, 1,6-hexylene,1,8-octylene, 1,12-dodecylene, 1,2-phenylene, 1,3-phenylene,1,4-phenylene, 1,2-naphthylene, 1,3-naphthylene, 1,4-naphthylene,1,6-naphthylene, 1,2-cyclopentylene, 1,3-cyclopentylene,1,2-cyclohexylene, 1,3-cyclohexylene or 1,4-cyclohexylene.

Component d) is preferably for example mercaptoacetic acid,mercaptopropionic acid, thiolactic acid, mercaptosuccinic acid, glycine,iminodiacetic acid, sarcosine, alanine, β-alanine, leucine, isoleucine,aminobutyric acid, hydroxyacetic acid, hydroxypivalic acid, lactic acid,hydroxysuccinic acid, hydroxydecanoic acid, dimethylolpropionic acid,dimethylolbutyric acid, ethylenediaminetriacetic acid, hydroxydodecanoicacid, hydroxyhexadecanoic acid, 12-hydroxystearic acid,aminonaphthalenecarboxylic acid, hydroxyethanesulfonic acid,hydroxypropanesulfonic acid, mercaptoethanesulfonic acid,mercaptopropanesulfonic acid, aminomethanesulfonic acid, taurine,aminopropanesulfonic acid, and their alkali metal, alkaline earth metalor ammonium salts, and with particular preference the abovementionedmonohydroxycarboxylic and monohydroxysulfonic acids and alsomonoaminocarboxylic and monoaminosulfonic acids.

To prepare the dispersion the aforementioned acids, if not already insalt form, are fully or partly neutralized, preferably using alkalimetal salts or amines, preferably tertiary amines.

Suitable component e) compounds are those which contain at least twoisocyanate-reactive groups, examples being —OH, —SH, —NH₂ or —NHR⁵, inwhich R⁵ is as defined above.

Compounds preferred for possible use as components e) have 2-10isocyanate-reactive groups, more preferably 2-6, very preferably 2-4,and in particular 2-3 isocyanate-reactive groups, preferably —OH or—NH₂, and very preferably —OH groups.

The compounds in question are, for example, polymers having a hydroxylgroup content of from 0.1 to 20% by weight, preferably from 0.5 to 10%by weight. The number average molecular weight M_(n) of the polymers ispreferably from 1000 to 100 000, more preferably from 2000 to 10 000.The polymers are preferably those composed of more than 50% by weight ofC₁-C₂₀ alkyl (meth)acrylate, vinylaromatics having up to 20 carbonatoms, vinyl esters of carboxylic acids containing up to 20 carbonatoms, vinyl halides, nonaromatic hydrocarbons having 4 to 8 carbonatoms and 1 or 2 double bonds, unsaturated nitriles, and mixturesthereof. Particular preference is given to the polymers composed of morethan 60% by weight of C₁-C₁₀-alkyl (meth)acrylates, styrene or mixturesthereof.

The polymers may additionally contain hydroxy-functional monomers inaccordance with the above hydroxyl content and, where appropriate,further monomers, examples being ethylenically unsaturated acids,especially carboxylic acids, acid anhydrides or acid amides.

Examples of further polymers are polyesterols as obtainable bycondensation of polycarboxylic acids, especially dicarboxylic acids,with polyols, especially diols.

Further suitable polymers include polyetherols, prepared by additionreaction of ethylene oxide, propylene oxide or butylene oxide withH-active components. Polycondensates formed from butanediol are alsosuitable.

The polymers can of course also be compounds having primary or secondaryamino groups.

Particularly preferred components e) are diols or polyols, such ashydrocarbon diols having 2 to 20 carbon atoms, e.g., ethylene glycol,1,2-propanediol, 1,3-propanediol, 1,1-dimethylethane-1,2-diol,1,6-hexanediol, 1,10-decanediol,bis-(4-hydroxycyclohexane)isopropylidene, tetramethylcyclobutanediol,1,2-, 1,3- or 1,4-cyclohexanediol, cyclooctanediol, norbornanediol,pinanediol, decalindiol, etc., their esters with short-chaindicarboxylic acids, such as adipic acid and cyclohexanedicarboxylicacid, their carbonates, prepared by reacting the diols with phosgene orby transesterification with dialkyl or diaryl carbonates, or aliphaticdiamines, such as methylene- and isopropylidenebis(cyclohexylamine),piperazine, 1,2-, 1,3- or 1,4-diaminocyclohexane, 1,2-, 1,3- or1,4-cyclohexanebis(methylamine), etc., dithiols or polyfunctionalalcohols, secondary or primary amino alcohols, such as ethanolamine,diethanolamine, monopropanolamine, dipropanolamine, etc., orthioalcohols, such as thioethylene glycol.

Also conceivable are diethylene glycol, triethylene glycol, dipropyleneglycol, tripropylene glycol, neopentyl glycol, pentaerythritol, 1,2- and1,4-butanediol, 1,5-pentanediol, 2-methyl-1,5-pentanediol,2-ethyl-1,4-butanediol, 1,2-, 1,3- and 1,4-dimethylolcyclohexane,glycerol, trimethylolethane, trimethylolpropane, trimethylolbutane,dipentaerythritol, ditrimethylolpropane, erythritol, and sorbitol,2-aminoethanol, 3-amino-1-propanol, 1-amino-2-propanol or2-(2-aminoethoxy)ethanol, bisphenol A, or butanetriol.

Likewise suitable are unsaturated polyetherols or polyesterols orpolyacrylatepolyols having an average OH functionality from 2 to 10, andalso polyamines, such as polyethyleneimine, for example, or polymerscontaining free amino groups and derived from poly-N-vinylformamide, forexample.

Particularly suitable here are the cycloaliphatic diols, such asbis-(4-hydroxycyclohexane)isopropylidene, tetramethylcyclobutanediol,1,2-, 1,3- or 1,4-cyclohexanediol, cyclooctanediol or norbornanediol,for example.

Compounds suitable as component f) are those having at least oneisocyanate-reactive group. These can be, for example, monoalcohols,mercaptans or monoamines having 1 to 20 carbon atoms, e.g., methanol,ethanol, iso-propanol, n-propanol, n-butanol, iso-butanol, sec-butanol,tert-butanol, ethylene glycol monomethyl ether, ethylene glycolmonoethyl ether, diethylene glycol monomethyl ether, diethylene glycolmonoethyl ether, 1,3-propanediol monomethyl ether, 1,2-propanediolmonoethyl ether, 1,2-propanediol monomethyl ether, n-hexanol,n-heptanol, n-octanol, n-decanol, n-dodecanol, 2-ethylhexanol,cyclopentanol, cyclohexanol, cyclooctanol, cyclododecanol, triethyleneglycol monomethyl ether, triethylene glycol monoethyl ether, n-pentanol,stearyl alcohol, cetyl alcohol, lauryl alcohol, cyclpent-2-en-1-ol,cyclopent-3-en-1-ol, cyclohex-2-en-1-ol, allyl alcohol, methylamine,ethylamine, iso-propylamine, n-propylamine, n-butylamine,iso-butylamine, sec-butylamine, tert-butylamine, n-pentylamine,n-hexylamine, n-heptylamine, n-octylamine, n-decylamine, n-dodecylamine,2-ethylhexylamine, stearylamine, cetylamine, laurylamine, dimethylamine,diethylamine, di-n-propylamine, di-iso-propylamine, di-n-butylamine,dihexylamine, dioctylamine, ethylmethylamine, iso-propylmethylamine,n-butylmethylamine, tert-butylmethylamine, iso-propylethylamine,n-butylethylamine, tert-butylethylamine, cyclopentylamine,cyclohexylamine, cyclooctylamine, cyclododecylamine, morpholine,piperidine, pyrrolidine, N-methylpiperazine, monoethanolamine,diethanolamine, monopropanolamine, dipropanolamine, methanethiol,ethanethiol, iso-propanethiol, n-propanethiol, n-butanethiol,iso-butanethiol, sec-butanethiol or tert-butanethiol.

As photoinitiators (C) it is possible to use those known to the skilledworker, such as those referred to in “Advances in Polymer Science”,Volume 14, Springer Berlin 1974 or in K. K. Dietliker, Chemistry andTechnology of UV and EB Formulation for Coatings, Inks and Paints,Volume 3; Photoinitiators for Free Radical and Cationic Polymerization,P. K. T. Oldring (Ed.), SITA Technology Ltd, London.

Suitable examples include phosphine oxides, benzophenones,α-hydroxyalkyl aryl ketones, thioxanthones, anthraquinones,acetophenones, benzoins and benzoin ethers, ketals, imidazoles or phenylglyoxylic acids, and mixtures thereof.

Phosphine oxides are for example monoacyl- or bisacylphosphine oxides,such as Irgacure® 819 (bis(2,4,6-trimethylbenzoyl)phenylphosphineoxide), as described for example in EP-A 7 508, EP-A 57 474, DE-A 196 18720, EP-A 495 751 or EP-A 615 980, such as2,4,6-trimethylbenzoyldiphenylphosphine oxide (Lucirin® TPO), ethyl2,4,6-trimethylbenzoylphenylphosphinate orbis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide;benzophenones are for example benzophenone, 4-aminobenzophenone,4,4′-bis(dimethylamino)benzophenone, 4-phenylbenzophenone,4-chlorobenzophenone, Michler's ketone, o-methoxybenzophenone,2,4,6-trimethylbenzophenone, 4-methylbenzophenone,2,4-dimethylbenzophenone, 4-isopropylbenzophenone, 2-chlorobenzophenone,2,2′-dichlorobenzophenone, 4-methoxybenzophenone, 4-propoxybenzophenoneor 4-butoxybenzophenone,

-   α-hydroxyalkyl aryl ketones are for example 1-benzoylcyclohexan-1-ol    (1-hydroxycyclohexyl phenyl ketone),    2-hydroxy-2,2-dimethylacetophenone    (2-hydroxy-2-methyl-1-phenylpropan-1-one), 1-hydroxyacetophenone,    1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propan-1-one or    polymer containing    2-hydroxy-2-methyl-1-(4-isopropen-2-ylphenyl)propan-1-one in    copolymerized form (Esacure® KIP 150);-   xanthones and thioxanthones are for example 10-thioxanthenone,    thioxanthen-9-one, xanthen-9-one, 2,4-dimethylthioxanthone,    2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone,    2,4-dichlorothioxanthone or chloroxanthenone;-   anthraquinones are for example β-methylanthraquinone,    tert-butylanthraquinone, anthraquinonecarboxylic esters,    benz[de]anthracen-7-one, benz[a]anthracen-7,12-dione,    2-methylanthraquinone, 2-ethylanthraquinone,    2-tert-butylanthraquinone, 1-chloroanthraquinone or    2-amylanthraquinone;-   acetophenones are for example acetophenone, acetonaphthoquinone,    valerophenone, hexanophenone, α-phenylbutyrophenone,    p-morpholinopropiophenone, dibenzosuberone,    4-morpholinobenzophenone, p-diacetylbenzene, 4′-methoxyacetophenone,    α-tetralone, 9-acetylphenanthrene, 2-acetylphenanthrene,    3-acetylphenanthrene, 3-acetylindole, 9-fluorenone, 1-indanone,    1,3,4-triacetylbenzene, 1-acetonaphthone, 2-acetonaphthone,    2,2-dimethoxy-2-phenylacetophenone,    2,2-diethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone,    1-hydroxyacetophenone, 2,2-diethoxyacetophenone,    2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one,    2,2-dimethoxy-1,2-diphenylethan-2-one or    2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butan-1-one;-   benzoins and benzoin ethers are for example    4-morpholinodeoxybenzoin, benzoin, benzoin isobutyl ether, benzoin    tetrahydropyranyl ether, benzoin methyl ether, benzoin ethyl ether,    benzoin butyl ether, benzoin isopropyl ether or 7H-benzoin methyl    ether; and-   ketals are for example acetophenone dimethyl ketal,    2,2-diethoxyacetophenone, or benzil ketals, such as benzil dimethyl    ketal.

Phenylglyoxylic acids are described for example in DE-A 198 26 712, DE-A199 13 353 or WO 98/33761.

Photoinitiators which can be used as well are for example benzaldehyde,methyl ethyl ketone, 1-naphthaldehyde, triphenylphosphine,tri-o-tolylphosphine or 2,3-butaned-ione.

Typical mixtures include for example

-   2-hydroxy-2-methyl-1-phenylpropan-2-one and 1-hydroxycyclohexyl    phenyl ketone,-   bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide and    2-hydroxy-2-methyl-1-phenylpropan-1-one, benzophenone and    1-hydroxycyclohexyl phenyl ketone,-   bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide and    1-hydroxycyclohexyl phenyl ketone,-   2,4,6-trimethylbenzoyldiphenylphosphine oxide and-   2-hydroxy-2-methyl-1-phenylpropan-1-one,-   2,4,6-trimethylbenzophenone and 4-methylbenzophenone or-   2,4,6-trimethylbenzophenone, and 4-methylbenzophenone and-   2,4,6-trimethylbenzoyldiphenylphosphine oxide.

As further typical coatings additivies (D) it is possible for example touse antioxidants, stabilizers, activators (accelerators), fillers,pigments, dyes, antistats, flame retardants, thickeners, thixotropicagents, surface-active agents, viscosity modifiers, plasticizers orchelating agents.

As accelerators for the thermal aftercure it is possible to use forexample tin octoate, zinc octoate, dibutyltin laurate ordiazabicyclo[2.2.2]octane.

In addition it is possible to add one or more photochemically and/orthermally activable initiators, examples being potassiumperoxodisulfate, dibenzoyl peroxide, cyclohexanone peroxide,di-tert-butyl peroxide, azobis-iso-butyronitrile, cyclohexylsulfonylacetyl peroxide, di-iso-propyl percarbonate, tert-butyl peroctoate, andbenzpinacol, and also, for example, those thermally activable initiatorswith a half-life at 80° C. of more than 100 hours, such as di-t-butylperoxide, cumene hydroperoxide, dicumyl peroxide, t-butyl perbenzoate,silylated pinacols, such as those available commercially under the tradename ADDID 600 from Wacker, or hydroxyl-containing amine N-oxides, suchas 2,2,6,6-tetramethylpiperidine-N-oxyl,54-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl, etc.

Other examples of suitable initiators are described in “PolymerHandbook”, 2^(nd) Ed., Wiley & Sons, New York.

Suitable thickeners besides free radically (co)polymerized (co)polymersinclude customary organic and inorganic thickeners such ashydroxymethylcellulose or bentonite.

As chelating agents it is possible for example to useethylenediamineacetic acid and its salts and also β-diketones.

Suitable fillers include silicates, e.g. silicates obtainable byhydrolysis of silicon tetrachloride, such as Aerosil® from Degussa,siliceous earth, talc, aluminum silicates, magnesium silicates, calciumcarbonates, etc.

Suitable stabilizers include typical. UV absorbers such as oxanilides,triazines, and benzotriazole (the latter obtainable as Tinuvin® gradesfrom Ciba-Spezialitatenchemie), and benzophenones. These can be usedalone or together with suitable free radical scavengers, examples ofwhich are sterically hindered amines such as2,2,6,6-tetramethylpiperidine, 2,6-di-tert-butylpiperidine orderivatives thereof, e.g., bis-(2,2,6,6-tetramethyl-4-piperidyl)sebacate. Stabilizers are used normally in amounts of from 0.1 to 5.0%by weight, based on the solid components present in the formulation.

The polyurethanes (A) of the invention are obtained by reactingcomponents a), b), and c) with one another.

In such a reaction the molar composition a):b):c) for each 3 mol ofreactive isocyanate groups in a) is generally as follows:

-   b) 0.1-2.9, preferably 0.5-2.8, more preferably 1.0-2.5, and    especially 1.5-2.5 mol of isocyanate reactive groups and-   c) 2.9-0.1, preferably 0.2-2.5, more preferably 0.5-2.0, and    especially 0.5-1.5 mol of isocyanate-reactive groups.

Following reaction of components a), b) and c) the polyurethane (A) maystill contain free or, where appropriate, blocked isocyanate groups,although preferably more than 30% of the isocyanate groups present in a)prior to the reaction have undergone reaction, more preferably more than50%, very preferably more than 60%, and in particular more than 65%.

When the polyurethanes are used in aqueous systems it is preferred forsubstantially all the isocyanate groups present to have undergonereaction.

In one preferred embodiment, particularly when the polyurethanes of theinvention are used in aqueous dispersions, polyurethanes of theinvention can include d), e) and/or f) as further synthesis componentsin the following amounts (per mole of reactive isocyanate group in thepolyurethane (A)):

-   d) 1-30 mol %, preferably 2-20 mol %, more preferably 3-15 mol %,    and especially 5-10 mol % of isocyanate-reactive groups,-   e) 0-50 mol %, preferably 5-40 mol %, more preferably 10-30 mol %,    and especially 15-25 mol % of isocyanate-reactive groups, and/or-   f) 0-50 mol %, preferably 5-40 mol %, very preferably 10-30 mol %,    and especially 15-25 mol % of isocyanate-reactive groups.

The formation of the adduct from isocyanato-functional compound and thecompound containing groups that are reactive toward isocyanate groups isgenerally accomplished by mixing the components in any order, whereappropriate at elevated temperature.

It is preferred to add the compound containing isocyanate-reactivegroups to the isocyanato-functional compound, preferably in two or moresteps.

Particular preference is given to introducing the isocyanato-functionalcompound as an initial charge and adding the compounds containingisocyanate-reactive groups. In particular first of all theisocyanato-functional compound a) is introduced, then b) andsubsequently c) are added, or first of all the isocyanato-functionalcompound a) is introduced, then c) and subsequently b) are added. Afterthat it is possible if desired to add further components which arewanted.

In another embodiment it is possible to prepare adducts (A1) from a) andb), and where appropriate d), e) and/or f), and adducts (A2) from a) andc), and also where appropriate d), e) and/or f), separately from oneanother and to react the components (A1) and (A2) thus obtainable at alater time, with the formation of adducts (A), for the purpose forexample of preparing a coating formulation or dispersion.

Generally speaking, the reaction is conducted at temperatures between 0and 150° C., preferably between 20 and 130° C., more preferably between25 and 120° C., and in particular between 40 and 100° C.

The reaction is generally performed in bulk (without solvent), insolution or in dispersion, preferably under atmospheric pressure.

Preference is given here to operating under water-free conditions.

Water-free means that the water content in the reaction system is notmore than 5% by weight, preferably not more than 3% by weight, and morepreferably not more than 1% by weight.

The reaction is preferably conducted in the presence of at least onesuitable inert gas, e.g., nitrogen, argon, helium, carbon dioxide or thelike.

The reaction can also be conducted in the presence of an inert solvent,e.g., acetone, iso-butyl methyl ketone, ethyl methyl ketone, toluene,xylene, butyl acetate or ethoxyethyl acetate.

Preferably, however, the reaction is conducted in the absence of asolvent.

The reaction is normally ended when the groups in the reaction mixturethat are reactive with NCO groups have undergone virtually quantitativereaction. Excess monomeric isocyanate is then removed by distillationunder reduced pressure, preferably down to a level below 1% by weight.

The NCO content as per DIN 53185 of the monomer-free polyurethanes (A)of the invention is preferably from 25 to 0% by weight.

Other reaction parameters are part of the skilled worker's generalknowledge and can be chosen for example in the manner described in EP-A585835, EP-A 496208, EP-A 69866, in U.S. Pat. Nos. 5,124,427, 5,258,482,and 5,290,902, and also DE-A-4015155 for the preparation of otherbiurets, allophanates, and isocyanurates.

Normally the monomers are reacted in the presence of a catalyst,preferably in amounts of from 10 to 5000 ppm by weight based on theamount of isocyanates employed.

Suitable catalysts include those widely known to catalyze the formationof adducts from isocyanate groups, i.e., for example, the quaternaryammonium hydroxides described in EP-A-649 866, such asN,N,N-trimethyl-N-(2-hydroxypropyl)ammonium hydroxide, or the quaternaryammonium carboxylates known from EP-A-182 203, such asN,N,N-trimethyl-N-(2-hydroxypropyl)ammonium 2-ethylhexanoate, ororganozinc compounds known to catalyze the formation of allophanates,such as zinc acetylacetonate or zinc 2-ethylcaproate.

As an alternative other organometallic compounds are used, viz. thosehaving at least one covalent metal-carbon bond, for catalyst purposes,examples being organic compounds of zirconium and bismuth.

The polyaddition of the abovementioned monomers for preparing thepolyurethane formulation of the invention can take place with particularpreference in the presence of cesium salts, as described in the olderGerman patent application of Dec. 12, 2001 with the application number10161156.0. Preferred cesium salts are compounds which use the followinganions: F⁻, Cl⁻, ClO⁻, ClO₃ ⁻, ClO₄ ⁻, Br⁻, I⁻, IO₃ ⁻, CN⁻, OCN³¹, NO₂⁻, NO₃ ⁻, HCO₃ ⁻, CO₃ ²⁻, S²⁻, SH⁻, HSO₃ ⁻, SO₃ ²⁻, HSO₄ ⁻, SO₄ ²⁻, S₂O₂²⁻, S₂O₄ ²⁻, S₂O₅ ²⁻, S₂O₆ ²⁻, S₂O₇ ²⁻, S₂O₈ ²⁻, H₂PO²⁻, H₂PO₄ ⁻, HPO₄²⁻, PO₄ ³⁻, P₂O₇ ⁴⁻, (OC_(n)H_(2n+1))⁻, (C_(n)H_(2n−1)O₂)⁻,(C_(n)H_(2n−3)O₂)⁻, and (C_(n+1)H_(2n−2)O₄)²⁻, in which n stands for thenumbers 1 to 20.

Particularly preferred are cesium carboxylates in which the anionconforms to the formulae (C_(n)H_(2n−1)O₂)⁻ and also(C_(n+1)H_(2n−2)O₄)²⁻, with n being from 1 to 20. Especially preferredcesium salts have monocarboxylate anions of the general formula(C_(n)H_(2n−1)O₂)⁻, in which n stands for the numbers 1 to 20. In thiscontext, particular mention may be made of the formate, acetate,propionate, hexanoate and 2-ethylhexanoate.

The cesium salts are used in amounts of from 0.01 to 10 mmol of cesiumsalt per kg of solvent-free batch. Preferably they are used in amountsof from 0.05 to 2 mmol of cesium salt per kg of solvent-free batch.

The cesium salts can be added to the batch in solid form but arepreferably added in dissolved form. As solvents, polar aprotic solventsor else protic solvents are suitable. Particularly suitable, in additionto water, are also alcohols; especially suitable are polyols, such asare also otherwise used as building blocks for polyurethanes, such asethanediols, propanediols, and butanediols, for example. The use of thecesium salts allows the polyaddition to be conducted under the standardconditions.

The progress of the reaction of polyurethane formation is appropriatelymonitored by gel permeation chromatography (GPC) or by determining theNCO content of the reaction mixture.

The reaction is normally ended when the starting compounds that arereactive with isocyanate groups have undergone virtually completereaction, i.e., are no longer detectable by GPC.

The normal way of ending the reaction is to add deactivators.

Examples of suitable deactivators include organic and inorganic acids,the corresponding acid halides, and alkylating agents. By way of examplemention may be made of phosphoric acid, monochloroacetic acid,dodecylbenzenesulfonic acid, benzoyl chloride, dimethyl sulfate, and,preferably, dibutyl phosphate and also di-2-ethylhexyl phosphate. Thedeactivators can be used in amounts of from 1 to 200 mol %, preferablyfrom 20 to 100 mol %, based on the moles of catalyst.

Especially preferred polyurethanes (A) are those having an allophanatecontent as determinable by gel permeation chromatography of from 0.5 to100 mol %, very preferably from 5 to 65 mol %, and in particular from 10to 50 mol %, based on the allophanate molecule with the lowest molecularmass.

Very much preferred polyurethanes (A) contain at least one of thefollowing compounds of the formula (II),

or higher homologs thereofwhere

-   R, R¹, R¹′, R², X, and Y are as defined above,-   Y′ can be as defined for Y but can also be different,-   R⁶ and R⁷ each independently are a divalent organic aliphatic,    cycloaliphatic or aromatic radical containing 2 to 20 carbon atoms    and unsubstituted or substituted by functional groups, aryl, alkyl,    aryloxy, alkyloxy, halogen, heteroatoms and/or heterocycles,-   R⁸ is hydrogen, methyl, ethyl or hydroxymethyl, and-   Z¹ and Z² can be identical or different and independently of one    another can be hydrogen or —(CO)—NH—R⁶—NCO.-   R⁶ radicals are for example the divalent radicals derived from the    abovementioned diisocyanates, such as 1,4-butylene, 1,6-hexylene,    1,8-octylene, 1,10-decylene, 1,12-dodecylene, 1,14-tetradecylene,    tetramethylxylylene, 2,4,4-trimethylhex-1,6-ylene,    2,2,4,4-tetramethylhex-1,6-ylene, 1,4-, 1,3- or 1,2-cyclohexylene,    di(cyclohexyl)methan-4,4′-ylene, di(cyclohexyl)methan-2,4′-ylene,    3,3,5,5-tetramethylcyclohex-1,5(1′)-ylene,    1,4-dimethylcyclohexan-1(1′),4(1″)-ylene,    1,3-dimethylcyclohexan-1(1′),3(1″)-ylene, 1-methylcyclohex-2,4- or    -2,6-ylene, 2,4- or 2,6-tolylene, m- or p-xylylene,    diphenylmethan-2,4′-ylene, diphenylmethan-4,4′-ylene, 1,3- or    1,4-phenylene, 1-chloro-2,4-phenylene, 1,5-naphthylene,    4,4′-diphenylene, 3,3′-dimethyldiphen-4,4′-ylene or    3-methyldiphenylmethan-4,4′-ylene.

Preferably R⁶ is 1,6-hexylene or3,3,5,5-tetramethylcyclohex-1,5(1′)-ylene and with particular preferenceit is 1,6-hexylene.

R⁷ is for example 1,2-ethylene, 1,2-propylene, 1,3-propylene,2-methyl-1,3-propylene, 2,2-dimethyl-1,3-propylene,2-ethyl-1,3-propylene, 2-hydroxy-1,3-propylene,2-hydroxymethyl-2-ethyl-1,3-propylene,2,2-bis(hydroxymethyl)-1,3-propylene, 1,4-butylene, 1,6-hexylene or2-ethyl-1,3-hexylene.

Preferably R⁷ is 1,2-ethylene, 1,4-butylene or 1,6-hexylene, morepreferably 1,2-ethylene or 1,4-butylene and very preferably1,2-ethylene.

-   Y′ is preferably oxygen (—O—).-   R⁸ is preferably hydrogen.-   n is preferably 2.

The polyurethanes of the invention are particularly suitable as binders,in for example coating compositions, surface coating materials orpaints.

The polyurethanes and polyurethane dispersions of the invention can beused with preference as coating compositions. For that purposecomponents (C) and, where appropriate, (D) are added to them wherenecessary.

Based on the overall weight the finished polyurethane dispersion cancontain 0-10% by weight of (C), preferably 1-8% by weight, morepreferably 2-7% by weight, and in particular 3-0.5% by weight.

Based on the overall weight the finished dispersion can contain 0-50% byweight of components (D), preferably 5-40% by weight, more preferably10-30% by weight, and especially 15-25% by weight.

The coating of the substrates is in accordance with customary methodswhich are known to the skilled worker, in which at least one coatingformulation or dispersion of the invention is applied to the targetsubstrate in the desired thickness and the volatile constituents of thedispersions are removed, where appropriate with heating. This operationcan be repeated one or more times if desired. Application to thesubstrate may take place in a known way, for example, by spraying,trowelling, knifecoating, brushing, rolling, roller coating, pouring,laminating, injection backmolding or coextruding. The coating thicknessis generally in a range from about 3 to 1000 g/m² and preferably from 10to 200 g/m².

Disclosed in addition is a method of coating substrates which involvesadding further typical coatings additives and thermally curable resinswhere appropriate to the polyurethane of the invention, to thepolyurethane dispersions of the invention or to coating formulations ofthe invention, applying the resultant systems to the substrate, anddrying them where appropriate, and curing them with electron beams or byUV exposure under an oxygen-containing atmosphere or preferably underinert gas, where appropriate at temperatures up to the level of thedrying temperature, and subsequently subjecting them to thermaltreatment at temperatures up to 160° C., preferably between 60 and 160°C.

The method of coating substrates can also be conducted such thatapplication of the polyurethanes or polyurethane dispersions or coatingformulations of the invention is followed first by their thermaltreatment at temperatures up to 160° C., preferably between 60 and 160°C., and subsequently by curing with electron beams or by UV exposureunder oxygen or preferably under inert gas.

Curing of the films formed on the substrate can if desired take place bymeans of heat alone. Generally speaking, however, the coatings are curedboth by exposure to high-energy radiation and thermally.

In addition to or instead of the thermal cure, curing may also beeffected by means of NIR radiation, which here means electromagneticradiation in the wavelength range from 760 nm to 2.5 μm, preferably from900 to 1500 nm.

If two or more coats of the coating composition are applied one aboveanother it is possible if desired for each coating operation to befollowed by an NIR, thermal and/or radiation cure.

Examples of suitable radiation sources for the radiation cure includelow pressure mercury lamps, medium pressure mercury lamps, and highpressure mercury lamps, and also fluorescent tubes, pulsed lamps, metalhalide lamps, electronic flash devices, which allow radiation curingwithout a photoinitiator, or excimer sources. The radiation cure iseffected by exposure to high-energy radiation, i.e., UV radiation ordaylight, preferably light in the wavelength (λ) range of 200 to 700 nm,more preferably 200 to 500 nm, and very preferably 250 to 400 nm, or byirradiation with high-energy electrons (electron beams; 150 to 300 keV).Radiation sources used are for example high pressure mercury vaporlamps, lasers, pulsed lamps (flashlights), halogen lamps or excimeremitters. The radiation dose normally sufficient for crosslinking in thecase of UV curing is in the range from 80 to 3000 mJ/cm².

It is of course also possible to use two or more radiation sources forcuring, e.g., two to four.

The sources may also each emit in different wavelength ranges.

Where appropriate, irradiation can also be carried out in the absence ofoxygen, e.g., under an inert gas atmosphere. Suitable inert gasesinclude preferably nitrogen, noble gases, carbon dioxide, or combustiongases. Irradiation may also be performed with the coating compositioncovered with transparent media.

Examples of transparent media are polymer films, glass or liquids, e.g.water. Particular preference is given to irradiation in the mannerdescribed in DE-A 199 57 900.

The invention further provides a method of coating substrates whichcomprises

-   i) coating a substrate with a coating formulation or dispersion as    described above,-   ii) removing volatile constituents of the coating formulation or    dispersion in order to form a film, under conditions in which the    initiator (C) as yet essentially forms no free radicals,-   iii) if desired, subjecting the film formed in step ii) to    high-energy radiation, in the course of which the film is precured,    and subsequently machining the article coated with the precured    film, if desired, or contacting the surface of the precured film    with another substrate, and-   iv) subjecting the film to a final thermal cure.

Steps iv) and iii) may also be carried out in the opposite order, i.e.,the film can be cured first thermally and then with high-energyradiation.

The coating formulations and dispersions of the invention areparticularly suitable for the coating of substrates such as wood, paper,textile, leather, nonwoven, plastics surfaces, glass, ceramic, mineralbuilding materials, such as cement blocks and fiber cement slabs, orcoated or uncoated metals, preferably for the coating of plastics ormetals, particularly in the form of films or foils.

With particular preference the dispersions or coating formulations ofthe invention are suitable as or in exterior coatings, i.e., in thoseapplications where they are exposed to daylight, preferably on buildingsor parts of buildings, interior coatings, traffic markings, coatings onvehicles or aircraft. The coating formulations or dispersions of theinvention are employed in particular as or in automotive clearcoat andtopcoat material(s).

The curing of the polyurethanes of the invention may for example involvethe following mechanisms:

-   mechanism 1, rapid: curing of double bonds with the aid of    high-energy radiation-   mechanism 2, slow: curing of the isocyanate groups by way of    atmospheric moisture-   mechanism 3, rapid: capped amines react with atmospheric moisture,    amine (and possibly alcohol as well) is released-   mechanism 4, very rapid: curing of NCO groups with amine-   mechanism 5, rapid: curing of NCO groups with alcoholic hydroxyl    groups-   mechanism 6, rapid: curing of the double bond with amine (Michael    addition)

Only mechanisms 1 and 2 are present in the case of conventional dualcure systems. In the case of the products according to the invention theslow reaction of NCO with water is significantly accelerated by theprior reaction of the capped amine with water and the subsequentreaction of NCO with amine. The amine produced also opens up thepossibility of reaction with the double bond.

A further advantage is that the films become harder as a result of thepurposive formation of ureas.

The examples below are intended to illustrate the properties of theinvention though without restricting it.

EXAMPLES

In this specification all parts unless specified otherwise are to beunderstood as parts by weight.

The viscosities were determined using a Rheolab MC 1 System, Z4 DIN,from Paar Physica at 23° C.

Example 1

0.5 mol of hexamethylene diisocyanate (HDI, i.e., 1 mol of NCO groups)in solution in 500 ml of dried methyl ethyl ketone was introduced as aninitial charge under nitrogen and 0.5 mol of hydroxyethyl acrylate and0.5 mol of 1-hydroxyethyl-2-isopropyl-1,3-oxazolidine (prepared inaccordance with DE-A 22 45 636) were added. The mixture was heated to70° C. and 200 ppm (based on HDI) of dibutyltin dilaurate were added.The reaction mixture was stirred at 70° C. for 1 hour and the solventwas then removed on a rotary evaporator. The melting point of the solid,NCO-free product was 70-80° C.

Example 2

Hexamethylene diisocyanate (HDI) was introduced as an initial chargeunder nitrogen and the amount of hydroxyalkyl (meth)acrylate specifiedin Table 1 was added. The mixture was heated to 80° C. and 200 ppm byweight (based on diisocyanate) of the catalystN,N,N-trimethyl-N-(2-hydroxypropyl)ammonium 2-ethylhexanoate were added.The temperature rose slowly to 120° C. The reaction mixture was left toreact at this temperature until the mixture had the NCO contentspecified in Table 1, at which point the reaction was stopped by adding250 ppm by weight (based on diisocyanate) of di-2-ethylhexyl phosphate.The reaction mixture was subsequently freed from unreacted HDI in a thinfilm evaporator at 1350C and 2.5 mbar.

End product data are included in Table 1. TABLE 1 NCO con- Amount NCOcon- tent af- Vis- Hydroxy- based on tent of ter dis- cosity Prod- Iso-alkyl isocya- mixture tillation at uct cya- (meth)acry- nate (% by (% by23° C. No. nate late (mol %) weight) weight) (mPas) 1 HDI HEA 5 40.820.1 520 2 HDI HEA 10 39.0 18.5 310 3 HDI HEA 15 35.6 17.4 290 4 HDI HEA20 33.3 16.3 260 5* HDI HEA 20 32.0 15.1 1,070 6 HDI HEA 35 18.5 13.05,530 7 HDI HEA 50 16.8 11.8 1,640 8 HDI HEMA 30 23.2 14.2 1,290Abbreviations:HDI = Hexamethylene diisocyanateHEA = Hydroxyethyl acrylateHEMA = Hydroxyethyl methacrylate*longer reaction time than for product 4

Example 3

200 g of product 4 from Example 2 with an NCO content of 16.3% wereintroduced as an initial charge under nitrogen and heated to 60° C. and123 g of 1-hydroxyethyl-2-isopropyl-1,3-oxazolidine were added over thecourse of 30 minutes. The reaction mixture was left to react at thistemperature for 1 hour. The end product (product 9) after cooling had aviscosity at 23° C. of 720 mPas.

Example 4

In the first stage of the reaction an HDI/HEA adduct as in product 5from Table 1 is prepared. In the subsequent stage it is reacted with1-hydroxyethyl-2-isopropyl-1,3-oxazolidine in accordance with thefollowing procedure:

-   2 drops of dibutyltin dilaurate (in 100% form) were added to 556.3 g    of HDI/HEA adduct (product 5 from Table 1) and the mixture was    heated to 60° C. Then slowly over the course of 30 minutes    1-hydroxyethyl-2-isopropyl-1,3-oxazolidine (30, 40 or 50 mol % based    on the analytical NCO value determined in accordance with DIN 53185)    was added. Stirring was continued at 60° C. for approximately 1    hour.

End product data are included in Table 2. TABLE 2 Oxazoli- dine HEA/HDI(mol %) NCO con- adduct in terms tent Product Product from of NCO (% byViscosity at No. Ex. 2 content weight) 23° C. (mPas) 10 5 30 9.0 9 11011 5 40 7.4 16 800 12 5 50 5.9 23 200 12b 5 100 0 >30 000

Example 5

Hexamethylene diisocyanate (HDI) was introduced as an initial chargeunder nitrogen and the amounts of hydroxyethyl acrylate and1-(2′-hydroxyethyl)-2-isopropyl-1,3-oxazolidine specified in Table 3were added. The mixture was heated to 80° C. and 200 ppm by weight(based on diisocyanate) of the catalystN,N,N-trimethyl-N-(2-hydroxypropyl)ammonium 2-ethylhexanoate were added.The mixture was allowed to react at this temperature for 30 minutes, atwhich point the reaction was stopped by adding 250 ppm by weight (basedon diisocyanate) of di-2-ethylhexyl phosphate. The reaction mixture wassubsequently freed from unreacted HDI in a thin film evaporator at 135°C. and 2.5 mbar.

End product data are included in Table 3. TABLE 3 HEA, Oxazolidine,amount based on amount based on Viscosity Product isocyanate isocyanateat 23° C. No. (mol %) (mol %) (mPas) 13 10 10 730 14 15 15 1150

Example 6

2000 g of hexamethylene diisocyanate (HDI) were introduced as initialcharge under nitrogen and reacted with 20 mol % ofN-(2-hydroxyethyl)-2-isopropyl-1,3-oxazolidine to give the allophanate.For this the mixture was heated to 80° C., 0.4 g of the catalyst DABCOTMR 1 (trade name of Air Products, N-(2-hydroxypropyl)trimethylammonium2-ethylhexanoate) was added, and reaction was allowed to continue atthis temperature until the mixture had an NCO content of 39-41% byweight, at which point reaction was stopped by adding 0.4 g ofdi-2-ethylhexyl phosphate. To remove monomeric HDI the reaction mixturewas subsequently distilled in a thin film evaporator at an oiltemperature of 165° C. and 2.5 mbar. The residual HDI monomer content ofthe end product was at this point under 0.5% by weight. The viscositywas 1700 mPas (product 15).

In the subsequent coating formulation the HDI/oxazolidine allophanateobtained (product 15) was mixed with product 5 from Table 1.

End product data are included in Table 4. TABLE 4 Amount of Amount ofProduct product 5 product 15 No. (mol %) (mol %) 16 50 50 17 33 67

The products according to the invention were cured with atmosphericmoisture or with UV irradiation with an atmospheric moisture aftercure.Coating mixtures of relatively high viscosity were diluted to 500 mPasusing butyl acetate (BuAc). The coating materials were drawn down ontoglass or metal sheet using film-drawing frames.

Test Methods:

-   -   pendulum damping (PD, in number of swings): coating on glass        substrate (DIN 53157) with a dry coating film thickness of about        30 μm in the case of air curing and about 50 μm in the case of        UV curing    -   Erichsen cupping (EC; DIN 53156, in mm of indentation): coating        material on Bonder panel 132 (dimensions 190×105×1 mm from        Chemetall): coating film thickness 25 to 30 μm    -   adhesion with cross-cut (Awc; DIN 53151, in ratings): coating        material on Bonder panel 132 (dimensions 190×105×1 mm from        Chemetall), dry coating film thickness 25 to 30 μm        UV Irradiation:

The films, flashed off where appropriate at room temperature to removesolvent, are irradiated 5 times under an IST high pressure mercury lamp(120 W/cm) with a belt speed of 10 m/min. TABLE 5 Curing without UVUrethane acrylate Laromer ® LR 8987 C2 1 from 2 from 3 from 4 from 8from Product (BASF AG) (comparative) Table 1 Table 1 Table 1 Table 1Table 1 Viscosity 4 000 12 300 520 310 290 260 2,920 (mPas) NCO value 012.8 20.1 18.5 17.4 16.7 15.8 (mg KOH/g) Coating 50 p product 50 pproduct 50 p product 50 p product 50 p product 50 p product 50 p productmaterial 8 p BuAc 8 p BuAc 1.5 p BuAc 0.5 p DBTL 0.5 p DBTL 0.5 p DBTL5.6 p BuAc formula 0.5 p DBTL 0.5 p DBTL 0.5 p DBTL 10% strength 10%strength 10% strength 0.5 p DBTL 10% strength 10% strength 10% strengthin BuAc in BuAc in BuAc 10% strength in BuAc in BuAc in BuAc in BuAc PDafter 24 h not curable 32 29 23 24 25 25 PD after 2 d 105 44 30 29 56 PDafter 5 d 142 54 32 30 61 PD after 7 d 30 138 49 32 31 68 PD after 14 d138 49 32 31 EC after 24 h 9 9 9 9 6.3 EC after 7 d 8.5 9 9 9 6.4Abbreviations:p: partsDBTL: dibutyltin dilaurateC2: Roskydal ® UA VP LS 2337 from Bayer, urethane acrylate based on HDIisocyanurateResult:

The allophanato acrylates cure without irradiation under the effect ofatmospheric moisture to give tack-free films. The films are highlyflexible. TABLE 6 Curing with UV Urethane acrylate C2 1 from 2 from 3from 4 from Product Laromer LR 8987 (comparative) Table 1 Table 1 Table1 Table 1 Viscosity 4 000 12 300 520 310 290 260 (mPas) NCO value 0 12.820.1 18.5 17.4 16.7 (mg KOH/g) Coating 50 p product 50 p product 50 pproduct 50 p product 50 p product 50 p product material 8 p BuAc 14.5 pBuAc 1.5 p BuAc 2 p Irgacure 184 2 p Irgacure 184 2 p Irgacure 184formula 2 p Irgacure 184 2 p Irgacure 184 2 p Irgacure 184 PD after 24 h128 42 46 69 71 63 PD after 7 d 129 139 146 144 144 143 EC after 24 h3.8 8.5 9 9 9 9 EC after 7 d 3.7 4.5 3.9 4 4 4, 4 AwC after 24 h 5 0 0 00 0 AwC after 7 d 5 1 1 1.5 0.5 1Irgacure ® 184 was obtained from Ciba Spezialitätenchemie.Result:

The low viscosity, allophanate based isocyanates display curingcharacteristics similar to those of the higher viscosity urethaneacrylate C2. Course of curing, flexibility, and adhesion to metal arecomparably good. After UV irradiation the allophanato acrylates havecured to a tack-free state. Under the effect of atmospheric moisturethere is a sharp increase in cure.

The urethane acrylate (Laromer) acquires its ultimate propertiesimmediately following irradiation. The adhesion to different substrates,however, is much poorer.

1. A polyurethane (A) comprising a) at least one organic diisocyanate orpolyisocyanate, b) at least one compound comprising at least oneisocyanate-reactive group and at least one free-radically polymerizableunsaturated group and/or cationically polymerizable group, c) at leastone compound comprising at least one isocyanate-reactive group and atleast one capped amino group and having a molecular weight below 1000g/mol, d) if desired, at least one compound containing comprising atleast one isocyanate-reactive group and at least one actively dispersinggroup, e) if desired, at least one compound comprising at least twoisocyanate-reactive groups, and f) if desired, compounds other than a)to d) comprising at least one isocyanate-reactive group, the allophanatefraction being 5 to 65 mol % based on the lowest molecular weightallophanate molecule.
 2. A polyurethane (A) comprising a) at least oneorganic diisocyanate or polyisocyanate, b) at least one compoundcomprising at least one isocyanate-reactive group and at least onefree-radically polymerizable unsaturated group and/or cationicallypolymerizable group, c) at least one compound comprising at least oneisocyanate-reactive group and at least one capped amino group and havinga molecular weight below 1000 g/mol, d) 1-30 mol % of at least onecompound comprising at least one isocyanate-reactive group and at leastone actively dispersing group, e) if desired, at least one compoundcomprising at least two isocyanate-reactive groups, and f) if desired,compounds other than a) to d) comprising at least oneisocyanate-reactive group.
 3. A polyurethane (A) comprising a) at leastone (cyclo) aliphatic organic diisocyanate or polyisocyanate, b) atleast one compound comprising at least one isocyanate-reactive group andat least one free-radically polymerizable unsaturated group and/orcationically polymerizable group, c) at least one compound comprising atleast one isocyanate-reactive group and at least one capped amino groupand having a molecular weight below 1000 g/mol, d) if desired, at leastone compound comprising at least one isocyanate-reactive group and atleast one actively dispersing group, e) no compound comprising at leasttwo isocyanate-reactive groups, and f) if desired, compounds other thana) to d) comprising at least one isocyanate-reactive group.
 4. Thepolyurethane (A) according to claim 1, wherein synthesis component c)has a molecular weight below 750 g/mol.
 5. The polyurethane according toclaim 1, comprising per 100 g of compound at least 0.01 mol ofunsaturated free-radically or cationically polymerizable groups and/orat least 0.01 mol of capped amino groups.
 6. The polyurethane accordingto claim 1, wherein said at least one capped amino group is selectedfrom the group consisting of open-chain aminals, cyclic aminals,ketimines, aldimines, N,O-acetals, N,O-ketals, carboxamides,sulfonamides, and amidines.
 7. The polyurethane according to claim 1,wherein component c) has the formula (I)

where R and R² independently are each a divalent organic aliphatic,cycloaliphatic or aromatic radical comprising 2 to 20 carbon atoms whichis unsubstituted or substituted by functional groups, aryl, alkyl,aryloxy, alkyloxy, halogen, heteroatoms and/or heterocycles, R¹ andR^(1′) independently are each hydrogen, C₁-C₁₈ alkyl, C₂-C₁₈ alkyl whichis uninterrupted or interrupted by one or more oxygen and/or sulfuratoms and/or by one or more substituted or unsubstituted imino groups,or are each C₆-C₁₂ aryl, C₅-C₁₂ cycloalkyl or a five- or six-memberedheterocycle containing oxygen, nitrogen and/or sulfur atoms, it beingpossible for each of said radicals to be substituted by functionalgroups, aryl, alkyl, aryloxy, alkyloxy, halogen, heteroatoms and/orheterocycles, X is oxygen (—O—), unsubstituted or monosubstitutednitrogen (—N(R⁴)—) or >N—NR⁴R⁵, Y is oxygen (—O—), unsubstitutednitrogen (—N(H)—) or sulfur (—S—), and R⁴ and R⁵ independently are eachhydrogen or C₁-C₄ alkyl.
 8. The polyurethane according to claim 1,comprising at least one of the following compounds of the formula (II)

or higher homologs thereof, where R and R² independently are each adivalent organic aliphatic, cycloaliphatic or aromatic radicalcomprising 2 to 20 carbon atoms which is unsubstituted or substituted byfunctional groups, aryl, alkyl, aryloxy, alkyloxy, halogen, heteroatomsand/or heterocycles, R¹ and R^(1′) independently are each hydrogen,C₁-C₁₈ alkyl, C₂-C₁₈ alkyl which is uninterrupted or interrupted by oneor more oxygen and/or sulfur atoms and/or by one or more substituted orunsubstituted imino groups, or are each C₆-C₁₂ aryl, C₅-C₁₂ cycloalkylor a five- or six-membered heterocycle containing oxygen, nitrogenand/or sulfur atoms, it being possible for each of said radicals to besubstituted by functional groups, aryl, alkyl, aryloxy alkyloxy,halogen, heteroatoms and/or heterocycles, X is oxygen (—O—),unsubstituted or monosubstituted nitrogen (—N(R⁴)—) or >N—NR⁴R⁵, Y isoxygen (—O—), unsubstituted nitrogen (—N(H)—) or sulfur (—S—), Y′ can beas defined for Y but can also be different, R⁶ and R⁷ each independentlyare a divalent organic aliphatic, cycloaliphatic or aromatic radicalcomprising 2 to 20 carbon atoms and unsubstituted or substituted byfunctional groups, aryl, alkyl, aryloxy, alkyloxy, halogen, heteroatomsand/or heterocycles, R⁸ is hydrogen, methyl, ethyl or hydroxymethyl, andZ¹ and Z² can be identical or different and independently of one anotherare hydrogen or —(CO)—NH—R⁶—NCO.
 9. A polyurethane dispersion comprising(A) a polyurethane according to claim 1 and comprising component d) and(C) if desired, one or more photochemically and/or thermally activableinitiators, and (D) if desired, further, typical coatings additives. 10.A coating composition comprising said polyurethane dispersion accordingto claim 9 and (C) if desired, one or more photochemically and/orthermally activable initiators, and (D) if desired, further, typicalcoatings additives.
 11. A method of coating a substrate, which comprisesradiation curing a substrate coated with said polyurethane as claimed inclaim 1, and thermally treating said polyurethane at temperatures up to160° C.
 12. The method according to claim 11, wherein said thermallytreating takes place between 60 and 160° C.
 13. The method according toclaim 11, wherein the radiation curing is conducted under inert gas. 14.A radiation-curable coating composition comprising said polyurethaneaccording to claim
 1. 15. A method for coating wood, metal or plastic,said method comprising coating said wood, metal, or plastic with saidpolyurethane according to claim
 1. 16. an automotive paint or automotivetopcoat material comprising said polyurethane as claimed in claim
 1. 17.A coating composition comprising said polyurethane (A) according toclaim 1 and (C) if desired, one or more photochemically and/or thermallyactivable initiators, and (D) if desired, further, typical coatingsadditives.
 18. A method for coating wood, metal or plastic, said methodcomprising coating said wood, metal, or plastic with said polyurethanedispersion according to claim 9.